| 摘要 |
The disclosure concerns the fabrication of integrated circuits. To enable the making, in an integrated circuit, of an internal clock, the frequency of which is adjustable and does not depend on the general supply voltage Vcc of the circuit, a relaxation oscillator is used. This relaxation oscillator is built in the following way: weighted individual current sources may be selectively connected in parallel under the control of a register containing frequency adjusting data. These sources charge and discharge a capacitor. A threshold comparator determines a high threshold Vh and a low threshold Vb to trigger respectively the discharging and the charging of the capacitor. The difference Vh-Vb is made proportional to the currents of the elementary sources. Thus, even if the value of the currents varies as a function of the supply voltage, the thresholds vary at the same time and the period of the oscillator does not vary.
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